Magnetic field dependence of the specific heat peak at 0.6–0.7°k in soft carbons

✍ Scribed by A.S. Vagh; S. Mrozowski

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 627 KB
• Volume: 13
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(75)90033-0

✦ Synopsis

The magnetic field dependence of the specific heat peak was investigated for a polycrystalline graphite of nuclear purity neutron irradiated for 50 hr and for a soft carbon heattreated to H'lT 1250°C. It was found that the relatively broader peak for irradiated graphite is located at 0.72"K and the sharper one for the soft carbon at 0.635"K.

In both cases the dependence on the magnetic field is similar, --the specific heat increases with the magnetic field from 0 to 20 kG in the whole range of temperature investigated (0.4-4,5"K), the increase on the high temperature side of the peak being greater than on the low temperature side. The peak's maximum shifts slightly to higher temperature with increase of the field (by 10% at 20 kG). The increase in the total specific heat at the peak's maximum is at 20 kG around 80% for the irradiated graphite and only 50% for the 1250°C carbon. It is shown that the peak is due to a cooperative ahtiferromagnetic interaction between localized electronic spins distributed at random throughout the material. The reasons for various complications in the overall effect are discussed.